1. Field of the Invention
The present invention relates to a method and apparatus for controlling a chiller, which is used for temperature-adjusting a processing apparatus, and particularly, to an energy-saving technique for efficiently reducing the energy consumed by the chiller. The present invention also relates to a semiconductor processing system having a thermo-medium circulation apparatus. The term “semiconductor process” used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a substrate, such as a semiconductor wafer or an glass substrate for an LCD (Liquid crystal display) or FPD (Flat Panel Display), by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the substrate.
2. Description of the Related Art
A plasma processing apparatus for a semiconductor process is a typical example of a processing apparatus employing a chiller. A plasma processing apparatus is widely used for a process, such as etching, deposition, oxidation, or sputtering, in the process of manufacturing semiconductor devices, LCDs, or FPDs. A plasma processing apparatus includes one or a pair of electrodes disposed in a reaction container or chamber, for generating plasma or attracting ions. The electrode(s) is supplied with a radio frequency (RF) power. In general, an electrode disposed at the center of the chamber and facing upward also functions as a worktable or susceptor for placing a substrate (a semiconductor wafer, glass substrate, or the like) thereon.
Since such a susceptor electrode comes into direct contact with a substrate, the electrode temperature has a direct influence on the substrate temperature, i.e., process temperature. Jpn. Pat. Appln. KOKAI Publication No. 2001-44176 discloses a structure in which a cooling medium room is formed in a susceptor electrode or in a conductive support member integrated therewith. A liquid or gaseous cooling medium set at a predetermined temperature is circulated and supplied into the cooling medium room from an outer chiller unit, so as to control the electrode temperature (see its FIG. 1).
Conventionally, without reference to whether a processing apparatus is in an ordinary operation for processing a substrate, or an idle state (in a resting phase), a chiller keeps supplying the processing apparatus with a cooling medium at a constant flow rate (i.e., a flow rate for maintaining the temperature of a susceptor electrode or substrate at a set temperature). In this case, the chiller consumes unnecessary energy. Generally speaking, a long idle state of a processing apparatus is brought about between respective lots. In this respect, production lines for large item and small volume, widespread in recent years, may irregularly fall into a long idle state (several tens of minutes or more, as the case may be) even between respective substrates, i.e., single substrate processes. Accordingly, energy consumption of a chiller cannot be ignored in recent years.